MH was performed in 12 fetuses: 2 with Ebstein anomaly, 2 with total anomalous pulmonary venous connection (TAPVC), 4 with hypoplastic left heart syndrome (HLHS) with (a) restrictive atrial septum (RAS) or (b) intact atrial septum (IAS) with decompressing vertical vein (VV), and 4 with D-loop transposition of the great arteries (TGA). PVr and physiologic and anatomic changes with MH and outcomes were recorded.